Brake fluid loss - mystery

[chrishewett]

I took the +2 for a hard drive on saturday. When I parked on the drive I noticed a line if fluid where I had reversed. On inspection it looked like brake fluid. Sure enough the master cylinder was a bit low. When I looked for a leak I found that the calipers were dry but I found fluid sprayed about around the alternator area, I thought that the alternator may have sprayed it about. The pipe from the servo was a bit wet and fluid had been on the front chassis cross member. I really couldn't see where the leak had obviously come from. I cleaned everything off and dried it. Sunday I took it for another drive and no leak!
This is really annoying as I would rather have an obvious falure that can be sorted than a failure waiting to happen.
Does anyone have any ideas why this may have happened?
The servo was new not long ago but could it be at fault?
Any suggestions gratefully received.
Chris

[M100]

Sound more like a coolant leak to me

[chrishewett]

It is not a coolant leak.
Chris

[1964 S1]

Had the car been sitting for awhile before your first drive? Perhaps brake fluid had puddled on the frame or somewhere and when the car moved, it drizzled off. I'll bet the leak is still there, just small and slow. Start a close inspection from the highest spot you found fluid. Does you pedal feel normal?

[miked]

Chris,

I am not sure about how it got were it did but re: your question about the servo. They can last years or just months. I posted a while ago about my servo. I found a fouled no 1 plug. Upon investigation I found a low master cylinder. I then found the air vac pipe all fouled up with fluid. Had I not noticed this it could have caused brake failure. There was not clouds of white smoke at the rear of the car, despite what i have heard. I talked to the expert who said that petrol vapour had destroyed the servo. Was only 2 years old. I had installed with the correct postioning of the pipe to act a sump for any fuel.

Was not impressed!

Solution: Fitted a modern one with two non return valves and upward facing air take off on the maifold. Also made large lower loop.

Mike

[berni29]

Hi

I am sure this is not the case with you, but on my first +2 the fan on the front of the alternator was just touching the brake line. Not when you looked, but when the engine was moving about with use.

I recently found my servo full of fluid, so I do not have much love for them at the moment.

Berni

[chrishewett]

Thanks for the comments. I will investigate further tomorrow and report back my findings.
Chris

[chrishewett]

I checked the car this morning and found no leak or evidence since last week. I then took it out and drove it fairly hard. The brakes are fine but maybe a little soft and pump up a bit harder. When I got back still no evidence of a leak. I hadn't topped up the reservoir since last week when it was definately a bit low. This is all very annoying as I want to iron out any problems before going to Hockenheim in april. Without doubt I lost some fluid last week.
I decided to top up the reservoir with the brake fluid I had in the garage ( I assume this is what was in it). When I looked it was Dot 4 synthetic. Does this sound right? I was worried about adding the wrong thing so I took some fluid out of the car and mixed it with the dot 4. It seems to mix without any separation sofar. I really can't remember what fluid was used before so I am now in a quandrey as to what to do next.
Any comments gratefully received.
Chris

[stuartgb100]

Chris,

Assuming you've wiped all the lines/hoses/unions etc and all is clean etc,
what about rigging some sort of brace to keep pressure on the brake pedal for a day or so (or overnight). Make a note of the level in the reservoir first.

I wouldn't worry about any cross-contamination until you've resolved the potential leak issue. After that, I'd definitely flush the system and refill.

You say the brake pedal pumps up.

Did it used to?

Regards,

Stuart.

[1964 S1]

Hello Stuart, your idea is great, I wonder what happened...
I'm just waiting for the day my +2's servos fail (slowly I hope) and then,,,off with their heads... I prefer the solid, yeah I've got them, brake pedal.

[chrishewett]

An update.
Yesterday I tried the heavy weight on the brake pedal. No leaks visible and no loss of fluid! Bugger! Now I still don't know what caused the original leak. I have to sheepishly admit that the fluid may have been oil from the dipstick. I will try the plug cap solution for that.
Meanwhile - brake fluid.
I have been reading some old posts on the subject and am a little confused. I have topped up with Comma dot 4 synthetic brake and clutch fluid. It mixes perfectly with the fluid in the system ( which is not suprising as it is probably the same). It says on the container that it mixes with other fluids meeting dot 3, dot 4, FMVSS.116 and SAEJ.1703. The question is - does synthetic mean silicon? Have I got a disaster waiting to happen? It doesn't mention silicon on the container but then it doesn't mention mineral either. From the previous posts it seems that silicon should not be used in the clutch system as it dissolves the seals but does this also apply to the brake system?
I hope someone can clear this up for me once and for all.
Chris

[ElliottN]

Chris - Silicone fluid is DOT 5. Synthetic does NOT mean silicone.

These days you will generally see DOT 3, DOT 4, SUPER DOT 4 and DOT 5 hydraulid fluids about.

The DOT 3, DOT 4 and SUPER DOT 4 fluids are polyglycol type fluids and get slightly more expensive as you move through the numbers. In turn though, they offer higher boiling points and ae less hydroscopic (absorb water less readily). DOT 3 and DOT 4 (and SUPER DOT 4) fluids can be mixed.

Mineral based fluids are something else altogether - pretty old I believe and I haven't hit a car yet that needs it.

DOT 5 shouldn't be mixed with anything but itself - it doesn't mix with other fluids and causes problems where the two fluids meet - there are lots of reports of damage to seals when DOT 5 is mixed with anything else.

Unless you're racing, DOT 4 is absolutely fine.

rgds,

[chrishewett]

Many thanks for that, I could not have heard better news!
Mind at rest now I think I will go and open that bottle of wine. Australian of course!
Chris